Granulating devices for thermoplastic materials having cutting blades on a cutting head are disclosed in DE-PS 14 54 888 and DE-PS 26 46 309.
In these granulating devices, an alignment of the cutting surfaces of the cutting blades in the cutting head is conducted prior to the actual granulating process by installing the cutting head so that the cutting blades are under slight pressure against the front face of the die plate attached to the granulating head of an extruder.
In this way, the cutting blades are brought in totality into exact alignment on the precision surface of the die plate and any deviations due to tolerances or the like are taken up. This is necessary in order to obtain a satisfactory granulate of uniform grain size.
The same initial conditions can be achieved in the same way after changing individual cutting blades in order to prevent changes in the quality of the granulate over a period of time of operation of the granulating device.
In order to prevent retraction of the cutting blades under the pressure produced by their alignment, the cutting blades are attached to the cutting head at a slight angle of incidence. Since the cutting blades can be removed individually, they can be reground at any time for a separate adjustment and future use. However, this is in fact only of conditional advantage since the new adjustment of the cutting blade after it is attached to the cutting head in a position of alignment with the die plate, a so called "cutting-in" operation, is very time consuming and requires a shutdown of several hours of granulate production.